On 31/08/09 22:28, Steven Dake wrote:
> On Mon, 2009-08-31 at 15:44 -0500, David Teigland wrote:
>> Here are two related and troublesome problems that would be nice to fix,
>> probably in future versions -- they probably can't be fixed maintaining
>> existing apis and protocols (although adding new api's to help with them 
>> might
>> be nice if possible).
>>
>> 1. correlating events from different services locally
>>
>> I get nodedown from both cman (or quorum service) and cpg.  I need to
>> correlate them with each other.  When I get a cpg nodedown for node A, I 
>> don't
>> know which cman nodedown for A it refers to: one of multiple in the past or
>> one in the future that cman hasn't reported yet.
>>
>
> Correlation could be solved by addition of api to cman, cpg, and quorum
> to retrieve the globally unique ring id for the last configuration
> change delivered to the application.
>

The quorum service already returns the ring ID :-)

Chrissie


> If you agree, we can work on the implementation for corosync 1.1.
> Adding this to CPG is trivial, not sure about other services.
>
> Our policies wrt x.y.z would not be violated with this change.
>
> As an example, the API for cpg might look like
>
> cpg_ringid_get (handle,&ring_id);
>
> Then ring_id could be memcmp'ed in the application.
>
> This would retrieve the last ring id delivered to the application (not
> the current ring id known to the cpg service).
>
>> 2. correlating events among nodes
>>
>> Some kind of global event/generation id associated with each configuration
>> that nodes can use to refer to the same event.  (For extra credit, make this
>> useful to detect the first configuration of a cpg across the cluster.)
>>
>
> define event here, you mean configuration change event or message
> delivery event?
>
>> Dave
>
>
>
> Regards
> -steve
>
>>
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